| 摘要 |
PURPOSE:To suppress the ring level value of an output signal at low level input, to make the output waveform stable and to prevent malfunction at poststages, by clipping a collector potential of a transistor TR to a forward voltage of a diode when an input voltage is in a low level. CONSTITUTION:A differential pair is formed by connecting the base of the 1st transistor (TR) Q2 to a signal input terminal IN via a diode D2 of forward connection, the base of the 2nd TRQ3 to a reference voltage and load resistors R3, R4 having equal resistance to the TRQ2, Q3, respectively. The base and the ground of the TRQ2 of the differential pair and are connected to a constant voltage clamp circuit comprising diodes D4-D8 and the TRQ1 and an emitter circuit comprising TRs Q4, Q5 connected to the collector of the TRQ2, Q3. The collector voltage of the TRQ1 when the input voltage is in a low level is clipped to the forward voltage of diodes D6, D7, the ring level value of the output signal at the low level is suppressed to the value at high level, and the output waveform is made stable. |
